抄録
The interdiffusion and intrinsic diffusion coefficients in Cu-rich Cu–Si alloys containing up to 8 at% Si have been determined in the temperature range between 900 and 1150 K by use of semi-infinite diffusion couples with the Kirkendall markers. Further, the tracer diffusion coefficient of 67Cu in pure Cu and the alloys containing up to 1.8 at% Si at 1130 K has been determined by the serial sectioning method. Non-linear enhancement of the Cu diffusivity in Cu–Si alloys by addition of Si has been observed, and the first and second order enhancement factors of the solvent diffusivity have been determined to be 19.4 and 188, respectively. The Gibbs free energy of binding between a vacancy and a silicon atom in Cu has been estimated to be −11.8 kJ mol−1 at 1130 K. Using the values of the self-diffusion coefficient in pure Cu and the extrapolated values of interdiffusion coefficient and intrinsic diffusion coefficient of Cu to the infinite dilution of Si, the vacancy flow factor in the Cu–Si system at 1130 K has been estimated to be −0.62. From the first order enhancement factor and the vacancy flow factor, appropriate numerical values of the correlation factor and the three jump frequency ratios in the five-frequency model for the impurity diffusion of Si in Cu have been evaluated. By combining the above data, the five frequencies have been also estimated. These results suggest a weak interaction between a vacancy and a silicon atom in Cu.
